The present invention relates to a valve arrangement for use in a container for discharging a fluid medium maintained under pressure in the container. The valve arrangement is used especially in cylindrical pressurized cans, includes a valve disk which can be connected in an opening in the container. The valve disk is pot-shaped and has a coupling device for a connection to an adapter of a discharging device.
In trade and industry, as well as in household use and many other applications, pressurized cans are used in which a fluid medium is maintained under pressure. The fluid medium may be a lacquer, a lubricant, a cleaning agent, a foaming medium, and the like. Such pressurized cans usually have an elongated shape with an open end closed by a valve arrangement. The valve arrangement includes a valve disk connected with an edge of the opening of the pressurized can and equipped with a discharging valve for the fluid medium. A discharging valve is formed with a valve body, a valve seat with a sealing element, a seal part and a restoring element. Frequently, the valve disk is pot-shaped and equipped with a device for connection to a container adapter so that the pressurized can be connected in a fluid type manner with a manual or motor-activated discharging device. A conventional valve arrangement is well known, for example, as disclosed in EP-B-O-350779. This known valve arrangement is intended in particular for aerosol cans formed of aluminum or sheet metal. Such cans or containers have a standardized opening with a diameter of about one inch. The opening has a rolled edge serving to accommodate the valve disk. The valve disk is inserted, and is positively connected with the container by bending. This bending process is usually referred to as xe2x80x9cclinchingxe2x80x9d or xe2x80x9ccrimping.xe2x80x9d
The valve disk forms a central part of such known valve arrangements and is formed of metal. The metal valve disk must be produced to fit exactly and, in mass production, requires expensive tools. For tightness reasons, the valve of the type disclosed in EB-P-O 350 779 has a plastics material valve seat. To produce such a metal valve disk, it must be placed in a plastics material injection mold where it is extrusion-coated with a plastics material. Aside from the additional expense of this manufacturing method, a gap may remain between the metal valve disk and the injection-coated plastics material allowing a path for the escape of an aerosol in the pressurized container. The connecting devices joining the pressurized container with the discharge device are limited to the cylindrical inner region of the pot-shaped valve disk and are formed with internal threads. Tools for producing an internal thread in the valve disk are relatively expensive and increase the cost of the manufacturing process. Moreover, many known discharging devices have standardized connection parts matched to the diameter of pressurized containers with external thread connections. As a result, separate adapters frequently are required for connecting known pressurized containers to such discharging devices. This is reflected in additional costs for manufacturing the unit and in increased assembly costs.
Therefore, a primary object of the present invention is to modify a known valve arrangement for a pressurized container so that the disadvantages previously experienced can be overcome. Accordingly, a valve arrangement is provided in which the danger of leakage is avoided. The manufacturing and assembly costs for such a valve arrangement are reduced and it is possible to provide a completed unit without separate adapter parts. In accordance with the present invention, a valve arrangement for delivering a fluid medium maintained under pressure in a container has the distinguishing features of a pot-shaped valve disk formed of a plastics material where the valve disk includes a generally cylindrical pot wall with a first wall extending transversally of the pot wall at one end and a second wall extending transversally at the opposite end with the second wall including a coupling device formed of the plastics material and located outwardly from the pot wall. A discharging valve is located within and spaced inwardly from the pot wall and includes a valve piston and a restoring element. Preferred variations and other developments form a part of the present invention. In general, a valve arrangement for discharging a fluid medium maintained under pressure in a cylindrical container includes the pot-shaped valve disk connected with the open end of the pressurized container and with a coupling device for a adapter of an discharging device. As mentioned above, the valve disk has a discharging valve, including a restoring element. The pot-shaped valve disk is formed of a plastics material and is plastically deformable, having a clinchable cylindrical pot wall. The coupling device is an integral connecting part, preferably a cylindrical external thread ring of plastics material connected by thin connecting cross members with a radially extending outer peripheral edge of the pot wall in the valve disk.
Since the pot-shaped valve disk, as a whole, is constructed as a plastics material part, subsequent injection coating of the valve disk with plastics material, such as required for the valve disks known in the state of the art, for sealing reasons and for corrosion protection, is unnecessary. As a result, gaps occurring between the metal valve disk and the injection-coated plastics material which can cause leaks from the pressurized container are avoided. The medium held in the pressurized container only contacts the plastics material valve disk. At the same time, the plastics material valve disk fulfills the sealing function. Such a valve disk is simple and can be manufactured and assembled in a cost-effective manner. The coupling device, required for assembly on a manual or motor-actuated discharging device, is formed integrally with the valve disk. Accordingly, the manufacture of the valve disk and the connecting part is performed in one step. The thin connecting cross-members, joining the connecting part with the plastics material valve disk, prevent the transfer of an impermissibly high torque or tilting movement in the valve disk. The connecting part may, for example, be in a bayonet catch. For manufacturing reasons, however, the connecting part is preferably formed as a cylindrical external thread ring. The thin connecting cross members are formed to break before the valve disk, clenched together with the edge of the opening of the pressurized container, is twisted relative to the pressurized container or lifted off by tilting. The maximum nominal torque capable of transfer by the thin connecting cross members is about 5Nm3. At larger torques, the cross members break. In the case of tilting, cross members have approximately the same strength. As a result, it is reliably prevented that the pressurized container is opened by faulty manipulation with the user coming into contact with the contents stored under pressure in the pressurized container.
The cross members, joining the connecting part with the valve disk are advantageously formed with break-off sites. With such arrangement, it is ensured, even with manufacturing variations in the wall thicknesses of the cross members, that the permissible torque and the permissible tilting moments are not exceeded.
To ensure that the connection between the valve disk and the edge of the opening in the pressurized can is reliably tight, the valve disk is greatly deformed during the clinching operation. Accordingly, valve disks with wall thicknesses in the region of the plastically deformable pot wall of about 0.2 mm to about 1.0 mm and preferably in the range of 0.3 mm to 0.8 mm have proven to be appropriate. With such wall thicknesses, depending on the plastics material used, a sufficient natural stiffness of the valve disk is assured and the forces, required for the deformation process during connection with the edge of the container opening, can be applied without further modification by known devices.
The arrangement of the valve disk with the integral connection part, particularly in the form of an external thread ring, makes it possible to use cost-effective manufacturing procedures. Preferably, the known injection molding method is employed making it possible to manufacture large quantities of the parts required both simply and rapidly.
To increase the tightness of the connection between the plastics material valve disk and the edge of the opening in the pressurized container, an additional subsidiary seal is used in another variation of the invention. The subsidiary seal is constructed as a ring-shaped, preferably elastic sealing lip, located adjacent and outwardly on the peripheral edge of the pot-shaped wall. The sealing lip may be formed as a pressure-supported sealing element exerting the sealing effect under pressure.
Relative to the direction of flow of the fluid medium after its passage through the valve seat, since the restoring element is not in constant contact with the pressurized medium in the container, there are a larger group of materials which can be used.
In one embodiment of the invention, the restoring element is constructed as a ring shaped or sleeve shaped member, the spring body is held elastically between a ring-shaped shoulder encircling the valve disk and a cylindrical piston guide extending axially relative to the valve disk. The ring shaped spring body is formed in direct continuation with the cylindrical piston guide. The material for use as the ring-shaped spring body is a thermoplastic elastomer which can be formed by injection molding. In addition, the spring body may be a separate part formed from a rubber-like material slipped onto the valve piston. The ring shaped spring body made of rubber or an elastomer, forms an additional seal when the pressurized container is connected to a discharging device. The spring body can also be formed as a metallic helical spring or from a similar element. The rubber-elastic spring bodies or elastic plastics material rings can rebound radially during the actuation of the discharging valve.
In a preferred embodiment of a pressurized container, equipped with the valve disk of the present invention, the pot-shaped disk, mounted at the edge of the opening, is reinforced by a cylindrical, preferably metallic reinforcing sleeve with a bottom section. The reinforcing sleeve is located inside the pot wall facing the valve arrangement and together with the valve disk is connected positively, particularly by clenching, with the edge of the opening of the pressurized container. Even in the case of valve disks which have little natural stability and because of the material used and wall thickness, the positive connection with the edge of the opening of the pressurized container is permanently assured by the reinforcing sleeve. The axial forces acting on the valve disk when the container is filled are reliably absorbed. The leakproofness remains guaranteed.
The pot-shaped reinforcing sleeve is preferably a simple deep-drawn part with a wall thickness of about 0.2 mm to about 0.5 mm and its surface quality and dimensional accuracy may not be very high. The cylindrical wall of the reinforcing sleeve supports the thin-pot wall of the plastics material valve disk. The bottom section of the reinforcing sleeve supports the lower wall of the disk which is under pressure. The tool and manufacturing costs of the reinforcing sleeve are relatively small.
The invention will now be explained in greater detail with the reference to the drawings, showing an embodiment example of the invention. In the drawings: